Comparative Analysis of Machining Characteristics of EDM ......experimental data as obtained through experimentation. The analysis of the experimental observations highlighted that

Comparative Analysis of Machining Characteristics of EDM and ECM

during Machining of Ti-6Al-4V

D.O.I - 10.51201/Jusst12626

http://doi.org/10.51201/Jusst12626

Sanjay1, S.S.Banwait

2

1PG Student, Department of Mechanical Engineering, National Institute of Technical Teachers Training

and Research (NITTTR), Chandigarh (India). 2Professor, Department of Mechanical Engineering, National Institute of TechnicalTeachers

Training and Research (NITTTR), Chandigarh (India).

Abstract

The present work explains the machining of Titanium alloy using Electric Discharge Machining &

Electro-Chemical Machining. This work aims to analyze the role of Current, Pulse on Time, Voltage and

hence optimize the Material Removal Rate and Surface Roughness in Electric Discharge Machining. In

the same way, it also aims to analyze the role of Concentration, Feed, and Voltage and optimize the

Material Removal Rate and Surface Roughness in Electro-Chemical Machining. The various

approaches like Taguchi & Analysis of Variance are executed to study the performance characteristics

of the input parameters on the output parameters. The whole work is followed by a validation test and

hence confirming the obtained values. Thus, it reveals the acceptability of the model. The work tells that

Material Removal Rate and Surface Finish effect is more in Electro-Chemical Machining as compared

to Electric Discharge Machining. For Material Removal Rate, Current and Feed are more responsible

parameters for Electric Discharge Machining. In the same way; electrolyte concentration and Feed are

more responsible parameters for Electro-Chemical Machining respectively.

Keywords:Titanium, EDM, ECM, Taguchi, ANOVA.

1. INTRODUCTION

The alpha-beta alloys, Ti-6Al-4V are by far the most popular titanium alloy. More than 50% of all alloys

in use today are of this composition. Grade 5 (Ti-6Al-4V) titanium alloy is an alpha-beta alloy that can

be heat treated to higher strength and heavier section size. Titanium alloy possesses excellent strength,

good corrosion resistance, and medium fabricability.

G. Kibria et al. [1] studied the effect of different types of dielectrics to find out its effects on the

machining outputs such as material removal rate (MRR), tool wear rate (TWR), overcut, diametral

variance at entry and exit hole, and surface integrity using EDM and ECM. Shailendra Kumar Singh et

al. Han-Ming Chow et al. [2] experimented by using two types of powders such as SiC and Al powder

in kerosene oil for investigating their effects on the machining output such as material removal rate

(MRR), tool wear rate (TWR), surface roughness, and the slit expansion. M. Ali Okay et al. [3]

conducted a set of EDM fast hole drilling operations to explore the effect of single and multi-channel

tubular electrodes on material removal rate, electrode wear, and microhardness. Lei Li et al. [4] studied

the effect of a bundled electrode on machining output. Different input parameters such as peak current,

fluid flow rate, pulse on-time, and pulse- off time were selected to investigate their effects on material

removal rate (MRR), tool wear rate (TWR). Ulas Caydas et al. [5] have carried out a study to optimize

the process parameters by applying different types of electrode materials. Khalid Hussain Syed et al. [6]

tries to optimize the process parameters so that maximum MRR, low EWR, higher surface finish, and

minimum white layer thickness can be achieved. K. K. Singh et al. [7] investigated the effect of

chromium powder on material removal rate, electrode wear rate, surface roughness, and white layer

thickness.

Journal of University of Shanghai for Science and Technology ISSN: 1007-6735

Volume 23, Issue 2, February - 2021 Page-346

Meena Laad et al. [8] investigated the enhancement in surface properties of Ti- 6Al-4V alloy machined

by EDM process by using graphite electrode. Gap current, pulse on time, and pulse off time were taken

as EDM process parameters and micro-hardness was taken as the response output. B. Bhattacharyya

et.al[9] Investigated controlled ECM through response surfacemethodology utilizing the relevant

experimental data as obtained through experimentation. The analysis of the experimental observations

highlighted that the MRR in ECM is greatly influenced by the various dominant process parameters such

as electrolyte concentration, electrolyte flow rate applied voltage inter-electrode gap considered in the

study. R V Rao et.al [10]studied that the selection of critical process parameters of ECM methods suchas

feed rate, the flow velocity of electrolyte, and voltage plays an important role in improving the measures

of process performance. These incorporate dimensional accuracies, MRR, machining cost, and tool life.

A particle optimization algorithm is exhibited to locate the optimal combination of process parameters

for the ECM process.

In the sum of the above analysis, it has been found that limited literature is available Comparative study

of EDM and ECM of titanium alloy. the workpiece material and tool material are same used in ECM and

EDM. but ECM and EDM different input parameters are suedes input parameters are used electrolyte

concentration, feed rate, and voltage. EDM input parameters are used current, pulse on time, and

voltage. The machining time is constant for both EDM and ECM processes.

2. MATERIAL & METHODS

Titanium alloy (Ti-6Al-4V, Grade 5) is used as workpiece material.The chemical composition of

titanium Ti-6Al-4V alloyis titanium 90%, aluminum 6%, iron 0.25% maximum, oxygen 0.2% maximum

and vanadium 4%.

Copper is used as an electrode tool material for machining titanium alloy material for EDM and ECM

processes. The copper tool diameter is 18 mm and the tool shape is circular for both EDM and ECM

processes. copper is a ductile metal. It should be electrically conductive and low electrical resistance.

Taguchi Method is used for an experiment for this process. The Design of Experiments chosen for the

ECM and EDM of Titanium alloy (Ti-6Al-4V) was a Taguchi L9 orthogonal array, consisting of a total

number of 9 trial of experiments.

Table 1Taguchi L9 Design

Current Pulse Voltage

1 1 1

1 2 2

1 3 3

2 1 2

2 2 3

2 3 1

3 1 3

3 2 1

3 3 2



Table 2 Experimental Data

current

(I)

Pulse

on time

(Ton)

Voltage(V)

MRR(g/min) Ra(µm)

SNRA1 SNRA2

11 99 38 0.0219 2.21 -33.1911 -6.88785

11 149 48 0.023 3.68 -32.7654 -11.317

11 199 58 0.0255 4.48 -31.8692 -13.0256

15 99 48 0.0272 5.68 -31.3086 -15.087

15 149 58 0.0346 4.46 -29.2185 -12.9867

15 199 38 0.0311 5.12 -30.1448 -14.1854

17 99 58 0.045 2.8 -26.9357 -8.94316

17 149 38 0.0562 5.64 -25.0053 -15.0256

17 199 48 0.0546 6.44 -25.2561 -16.1777

Analysis of input factors that affect the MRR and surface roughness of Titanium alloy in ECM is

described Below.

The Response table for the signal to noise ratios MRR is shown in table 3 and the corresponding

ANOVA Table is shown in Table 4.MRR, the calculation of S/N ratio follows larger is a better model.

Table.3 Response table for the signal to noise ratios MRR

Level Current (I) Pulse on time

(Ton)

Voltage (V)

1 -32.61 -30.48 -29.45

2 -30.22 -29.00 -29.78

3 -25.73 -29.09 -29.34

Delta 6.88 1.48 0.44

Rank 1 2 3

Table 3 specified the average effect response tables for obtained data and S/N ratio, these tables help us

find out which parameters will affect more significantly. As shown in table 3 maximum and minimum

difference peak current, pulse on time, and applied voltage are ranked 1,2,3, respectively. so it is

concluded that the peak current has a major effect on MRR quality than pulse on time and voltage.

A general linear model of ANOVA was used to conduct an ANOVA test which requires a response and

the factors affecting the response. Table 4 results of the analysis of variance for MRR for S/N data which

specify signal of different parameters on the MRR are summarized as below.



Table 4 ANOVA for MRR

Source D.O.F SS Contribution Adj SS A Dj MS F-Value P-Value

Current 2 0.001306 92.39% 0.001306 0.000653 48.01 0.020

Pulse on time 2 0.000076 5.40% 0.000076 0.000038 2.81 0.263

Voltage 2 0.000004 0.28% 0.000004 0.000002 0.15 0.871

Error 2 0.000027 1.92% 0.000027 0.000014

Total 8 0.001414 100.00%

Figure 2. S/N Ratio Curve For MRR

As seen in the response and S/N ratio effect graph, peak current has a strong effect on MRR and their

S/N ratio. The pulse on-time and voltage have a smaller effect, which is evident from the shallow slope

of the lines. the graph indicates the levels at which the S/N ratio and MRR effect are at their optimal

magnitude; that is, their S/N ratio effect is at its highest magnitude and the MRR effect is at its largest

magnitude. From fig.2.MRR increases when pulse on time is increased.

The Response table for the signal to noise ratios Surface Roughness is shown in table 5 and the

corresponding ANOVA Table is shown in Table 6. Surface Roughness, the calculation of S/N ratio

follows smaller is a better model.

Table 5 Response table for the signal to noise ratios Surface Roughness

Level Current Pulse on Time Voltage

1 -10.41 -10.31 -12.03

2 -14.09 -13.11 -14.19

3 -13.38 -14.46 -11.65

Delta 3.68 4.16 2.54

Rank 2 1 3





difference peak current, pulse on time, and applied voltage are ranked 1,2,3, respectively. so it is

concluded that the peak current has a major effect on surface quality than pulse on time and voltage.


the factors affecting the response. Table 6 results of the analysis of variance for surface roughness for

S/N data which specify signal of different parameters on the surface roughness are summarized as

below.

Table 6 ANOVA for Surface Roughness

Source D.O.F SS Contribution Adj SS Adj MS F-Value P-Value

Current 2 4.933 31.52% 4.933 2.466 1.63 0.380

Pulse on

time

2 4.809 30.73% 4.809 2.404 1.59 0.386

Voltage 2 2.889 18.46% 2.889 1.445 0.96 0.511

Error 2 3.017 19.28% 3.017 1.509

Total 8 15.648 100.00%

Figure 3. S/N Ratio Curve for Surface Roughness

As seen in the response and S/N ratio effect graph, pulse on time has a strong effect on surface

roughness and their S/N ratio. The peak current and voltage have a smaller effect, which is evident from

the shallow slope of the lines. the graph indicates the levels at which the S/N ratio and surface roughness

effect are at their optimal magnitude; that is, their S/N ratio effect is at its highest magnitude and the

surface roughness effect is at its smallest magnitude. From fig. 3 surface roughness increases when pulse

on time is increased.

Table 7 Results of confirmation test for MRR and surface roughness in EDM

Response parameter Experimental value Predicated value Error%

MRR 0.0562 0.0577 2.67

Surface roughness 2.21 2.13 3.76

The error between Predicted MRR & Experimental MRR is 2.67 % i.e., below 5%. Thus, the work is

validated. In the same way, the error between Predicted Ra & Experimental Ra is 3.76 % i.e., below 5

%. Hence, the work is validated & acceptable. Analysis of input factors that affect the MRR and surface

roughness of Titanium alloy in ECM is described below.



Table 8 Experimental Data

Concentration Feed Voltage MRR Ra SNRA1 SNRA2

(g/ltr) (mm/min) x10-3 (v) (g/min) µm

150 144 15 0.136 6.4 -17.3292 -16.1236

150 180 20 0.033 1.93 -29.6297 -5.71115

150 240 25 0.096 0.71 -20.3546 2.974833

200 144 20 0.153 7.3 -16.3062 -17.2665

200 180 25 0.077 1.94 -22.2702 -5.75603

200 240 15 0.098 0.92 -20.1755 0.724243

250 144 25 0.145 11.52 -16.7726 -21.229

250 180 15 0.078 2.27 -22.1581 -7.12052

250 240 20 0.161 6.67 -15.8635 -16.4825

The Response table for the signal to noise ratios MRR is shown in table 9 and the corresponding

ANOVA Table is shown in Table 10 MRR, the calculation of S/N ratio follows larger is a better model.

Table 9 Response table for the signal to noise ratios

Level Concentration Feed rate Voltage

1 -22.44 -16.80 -19.89

2 -19.58 -24.69 -20.60

3 -18.26 -18.80 -19.80

Delta 4.17 7.88 0.80

Rank 2 1 3



difference electrolyte concentration, feed rate, and applied voltage are ranked 1,2,3, respectively. so it is

concluded that the electrolyte concentration has a major effect on MRR quality than feed rate and

voltage.


the factors affecting the response. Table 10 results of the analysis of variance for MRR for S/N data

which specify signal of different parameters on the MRR are summarized as below.

Table 10 ANOVA for MRR

Source D.O.F A A F-V P-V

Concentration 2 0.002363 0.001181 1.48 0.404

Feed rate 2 0.010516 0.005258 6.57 0.132

Voltage 2 0.000234 0.000117 0.15 0.873

Error 2 0.001602 0.000801

Total 8 0.014714



Figure. 3 S/N Ratio Curve For MRR

As seen in the response and S/N ratio effect graph, electrolyte concentration has a strong effect on MRR

and their S/N ratio. The feed rate and voltage have a smaller effect, which is evident from the shallow

slope of the lines. the graph indicates the levels at which the S/N ratio and MRR effect are at their

optimal magnitude; that is, their S/N ratio effect is at its highest magnitude and the MRR effect is at its

largest magnitude. From fig.4 MRR increases when electrolyte concentration is increased.

The Response table for the signal to noise ratios Surface Roughness is shown in table 11 and the

corresponding ANOVA Table is shown in Table 12 Surface Roughness, the calculation of S/N ratio

follows smaller is a better model.

Table 11 Response table for the signal to noise ratios

Level concentration Feed rate Voltage

1 -6.287 -18.206 -7.507

2 -7.433 -6.196 -13.153

3 -14.944 -4.261 -8.003

Delta 8.657 13.945 5.647

Rank 2 1 3



difference electrolyte concentration, feed rate, and applied voltage are ranked 1,2,3, respectively. so it is

concluded that the electrolyte concentration has a major effect on surface quality than feed rate and

voltage.


the factors affecting the response. Table 12 results of the analysis of variance for surface roughness for

S/N data which specify signal of different parameters on the surface roughness are summarized as

below.



Table 12 ANOVA for Surface Roughness

Source D.O.F Adj SS Adj MS F-Value P-Value

Concentration 2 26.418 13.209 6.02 0.142

Feed rate 2 72.778 36.389 16.58 0.057

Voltage 2 7.087 3.544 1.61 0.382

Error 2 4.390 2.195

Total 8 110.673

Figure4 S/N Ratio Curve For surface roughness

As seen in the response and S/N ratio effect graph, electrolyte concentration has a strong effect on

surface roughness and their S/N ratio. The feed rate and voltage have a smaller effect, which is evident

from the shallow slope of the lines. the graph indicates the levels at which the S/N ratio and surface

roughness effect are at their optimal magnitude; that is, their S/N ratio effect is at its highest magnitude

and the surface roughness effect is at its smallest magnitude. From fig.5.surface roughness increases

when electrolyte concentration is increased.

Table 13 Results of confirmation test for MRR and surface roughness in ECM

Response parameter Experimental value Predicated value Error%

MRR 0.161 0.164 1.86%

Surface roughness 0.71 0.70 1.41%

The error between Predicted MRR & Experimental MRR is 1.86 % i.e., below 5%. Thus, the work is

validated. In the same way, the error between Predicted Ra & Experimental Ra is 1.41 % i.e., below 5

%. Hence, the work is validated & acceptable.

Economic analysis, considering the Material cost, Tool cost, Dielectric fluid, Power consumption and

Machining cost.



Table 14 Economic analysis for both EDM and ECM

Sr.

No.

Cost EDM ECM

1 Workpiece cost 1399.50 1399.50

2 Tool cost 250 250

3 Dielectric fluid/electrolyte cost 115 1800

4 Power consumption 50 50

5 Total Machining cost 1814.50 3499.50

Economic analysis for both EDM and ECM, the workpiece material cost is the same, and tool cost is the

same. The machining cost, ECM is more costly as comparison of EDM, because of electrolyte iscostly.

Thetwo or more (NaCl, NaNO3) type of electrolyte are used and in the case of EDM,EDM-oil is used as

dielectric fluid. EDM oil cost is less in comparison to ECM electrolytic is a more time-consuming

process as compare to EDM Because different electrolytes are used.

3. RESULTS AND DISCUSSION

As MRR is more in the case of ECM as compared to EDM. Thus, we can say that ECM helps in more

machining of Titanium as compared with EDM. Also, the surface roughness of Titanium with the

machining of ECM is less as compared to EDM. Thus, ECM provides better surface finishing to

Titanium during machining. Overall, we can say that ECM plays a better role in providing good

machining & a better surface finishing to titanium.

4. CONCLUSION

The optimum input parameters for high MRR in EDM in titanium alloy obtained were 0.0562mm/min,

peak current is 17 A, pulse on time is 149µsec, applied voltage is38v. The experimental value of MRR

obtained is 0.0562 mm/min .and the predicted value is 0.0577 mm/min. The percentage error is 2.67%

which is well with the permissible limit.

The optimum input parameters for low surface roughness in EDM in titanium alloy obtained were 2.21

µm, peak current is 11A, pulse on time is 99 µsec, the applied voltage is 38v. The experimental value of

surface roughness obtained is 2. 21µm.and the predicted value is 2.13µm. the percentage error is 3.76%

which is well with the permissible limit.

The optimum input parameters for high MRR in ECM in titanium alloy obtained were 0.161mm/min,

electrolyte concentration is250 g/ltr, the feed rate is 240 mm/min, the applied voltage is 20v.The

experimental value of MRR obtained is 0.161 mm/min .and the predicted value is 0.164mm/min. The

percentage error is 1.86% which is well with the permissible limit.

The optimum input parameters for low surface roughness in ECM in titanium alloy obtained were 0.71

µm, electrolyte concentration is150 g/ltr, the feed rate is 240 mm/min, the applied voltage is 25v. The

experimental value of surface roughness obtained is 0. 71µm.and the predicted value is 0.70µm. the

percentage error is 1.41% which is well with the permissible limit.



Acknowledgment

This experimental work is supported by the National Institute of Technical Teachers’ Training and

Research (NITTTR), Chandigarh (India).

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Documents

Comparative Analysis of Machining Characteristics of EDM ......experimental data as obtained through experimentation. The analysis of the experimental observations highlighted that